1. Field
The following description relates to a mobile communication technology, and more particularly, to a technology for mitigating the inter-cell interference.
2. Description of the Related Art
Recently, technologies for 4th generation (4G) mobile communications have been actively studied. Especially, technologies regarding an expansion of transmission bandwidth, an advanced multi-antenna, improvement of uplink capacity, and mitigation of inter-cell interference have been researched. In 4th generation mobile communications, the importance of inter-cell interference mitigation is increasing in terms of supporting a microcell for high frequency, a femtocell located in a building or a private area and providing a given user with a high transmission rate and a wireless relay to be located on a border region of cells to increase base station coverage area.
Various types of cells having small service areas cause increase of overlapping cell regions which are significantly affected by inter-cell interference, and thus a technique for controlling the inter-cell interference becomes prerequisite for improving data rate of a system.
A soft frequency reuse (SFR) technique is for increasing data transmission rate of a user equipment (UE) that is located on the border of a cell and considerably interfered by an adjacent cell. SFR technique is generalized from a fractional frequency reuse (FFR) technique, and in which each adjacent cell sets transmission powers for individual sub-bands differently from one another so that data transmission rate of the UE located on the border of the cell thus being significantly interfered by the adjacent cell can be increased.
Additionally, if a frequency reuse index of 1 is used, all cells use the same frequency and hence inter-cell interference becomes greater, while frequencies can be used to the maximum and consequently the system efficiency is increased. On the other hand, when the frequency reuse index is raised, the inter-cell interference is reduced but wastage of frequency resources is increased.